1. Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
2. Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, Italy
3. Departments of Chemistry, Materials Science & Engineering, Biomedical Engineering and Pharmacology, Northwestern University, Evanston, Illinois 60208, United States
4. Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, California 92093, United States
5. Istituto di Fotonica e Nanotecnologie (IFN)−Consiglio Nazionale delle Ricerche (CNR), Piazza Leonardo da Vinci 32, 20133 Milano, Italy